Testing by the agency found that the vehicles originally submitted mpg totals were off slightly. Specifically, the miles per gallon performance in city driving was originally 20 for the FFV and PZEV. The agency revised them to 19.

The EPA also lowered the PZEV's mpg performance for highway driving to 28 from 29. The revisions led to a reduction in the PZEV's combined city-highway mpg to 22 from 23.

The German automaker did not immediately respond to a request for comment Wednesday.